Inside a mason bee nest

Harvesting cocoons from Corn Quicklock trays is fun.  You open two pieces of interlocking trays and you see what is inside.  Every row tells its own story and often it is a very different from the adjacent nesting tunnel.  It is great to see bees at work, but it is very exciting to see what they have produced and to see what other insects are using these nesting tunnels as their home.

This pink larvae has a brown head capsule.  It feeds on any detritus and pollen in the tunnel.  If left inside over the winter, it can chew through cocoons and destroy your bees.  After it has spun its cocoon, it emerges again during the early summer as a moth.  I remove these grubs from the nest as I harvest mason bee cocoons.

The warmth of the room where we harvested the mason bee cocoons warmed up the larvae and made it active.  It was travelling around the tray as I photographed it.  In the foreground are two mud walls dividing two cells each containing a male bee cocoon.  The female cocoon usually fills the space between the walls of the nesting tunnel.  Each cocoon is covered in frass and some mites.





Here is the larvae spinning its web  for its overwintering period.

This morning I received an email from Norm
Subject: cocoon removal
“ I have the cardboard tubes with liners.
 Is it possible to remove the cocoons from this type nest?”

Answer:
Yes it is possible.  First try pulling out the liners.  If the liner is dry, you can remove the liner and replace the tube with a clean liner.  Unfortunately if there is any moisture, the liner absorbs moisture and breaks when you try and remove the liner.  If this happens, the cardboard tube has to be unraveled to get the cocoons out.

This nesting tray contains 5 nesting tunnels.  The upper nesting tunnel contains cocoons with a mud partition between each cocoon.  The mud plug at the left hand side of the nesting tray indicates the entrance /exit.  The larger or female cocoons are at the back of the tunnel (RHS).  Note in the next two nesting tunnels, there are quite a number of compartments, not with a cocoon, but with a pollen lump.

The presence of a pollen lump means that the bee larvae died and did not continue its development into an adult bee.  This can be caused by disease, but can also be caused by cool weather.  Young bees need warmth to feed.  A two week spell of cold weather usually means the demise of these bees.  Unfortunately in this case, the pollen lumps were at the far end of the tunnel and these are the female bees.

This year, many people were not able to produce many mason bee cocoons.  I am sure the weather played a big part in this story.

I’m writing to tell you briefly about our 2010 harvest, and also am sending some images of weird and wonderful things that we encountered in the process.
As for the harvest itself, I’m not going to send you all the data but will simply summarize.
I had 13 people in the group this year.  Altogether we set out 3110 cocoons, and  we harvested 3124.  Not a banner year by any means, but at least sustainable.  
Here are some photos.  I’d be pleased to receive any comments or suggestions about these, Margriet.  It seems that every year we find something more weird and more wonderful than ever.  
I should also mention that I’m using the stainless-steel-screen technique to remove additional mites after washing.  I did it the first time an hour or so after washing and drying, with very good results, I’ll do it again this month while they’re in storage, and a final time when I take them out of storage to distribute to the members of our group..
This photo (below) is of a group of 15 strange rusty coloured cocoons that we found in just one tray from a nesting box on Galiano Island. They seem to be covered with sticky pollen or something that stains the fingers.  Image 009 shows how the cocoon material itself is sort of layered.  When I tried to open some of them I found that there was an outer layer that peeled away, with some sort of cocoon-like structure underneath.  Inside that I found only a thick creamy coloured fluid that oozed out.  Any ideas? 
COMMENTS:  This is a species of summer mason bees, that uses masticated leaf materials for its chamber construction.  I have never opened one, so it is interesting to note that the content is still in the pupal stage of development.  The final stage of development would occur when warmer weather begins in spring.
This photo (below) shows a gallery with eight compartments constructed from pine resin, for goodness sakes!!.  Four of them have tiny caterpillars in them.  They look superficially like the ones in Image 002 but they are much smaller.  There is no doubt about the pine resin (or some conifer), because it was sticky to remove and as I worked it I could smell the familiar fragrance.  Again, any ideas?
COMMENTS:  This looks likes some resin bees in the pupal stages of development.  They would develop into an adult resin bees and emerge in the summer when the resin is soft.
This photo (below) shows wiry brown frass completely filling a compartment.  There were two or three of these compartments. The entomologists at the Museum thought it might be fly frass.  Never seen it before.
COMMENTS:  Does anyone have any ideas on this one?
The photo below shows how easily the mites can travel from one gallery to another.  
COMMENTS: The brown-reddish granules are the pollen feeding mites.  One or two or more land in the chamber in spring and mites consume the pollen.  What you get is a million mites and no bee.
This photo (below) shows another type of caterpillar.
COMMENT:  It could be a beneficial wasp pupae. 
This shows (below) a cocoon completely covered with dark brown rods of frass.  The question is .. whose frass is it and how could it have been placed while the cocoon was completely enclosed by mud and the overlying tray??  I’ve cropped the image so you can see it better.
COMMENTS:  When a mason bee spins its cocoon, it leaves its frass on the outside of the cocoon.  The different colours of pollen indicates that multiple species of plants were visited when collecting the pollen.
This photo (below) shows large creamy coloured ‘caterpillars’. 
COMMENTS:  This compartment contains no bee, although it is the compartment made by a mason bee.  These grubs were laid in the compartment while the female mason bee was completing the construction of the compartment.  The brown stringy frass may belong to this insect.

 NOTE:  Usually I would not disturb the cocoons and the pupae like the resin bees, but close up the nest and set the nest outside.  The reddish frass and the multiple pupae in one cell, looks like it came from a predator of some kind and I would remove it from the nesting tunnels.

Photo #1.  Joe S. from Burnaby, BC showed me this interesting occupant of his Beediverse Quicklock nesting trays. The photo above shows 2 nesting tunnels.  The upper tunnel shows a common sight.  It looks like sawdust, but actually is a collection of pollen feeding mites amongst pollen. The lower tunnel contains a mason bee cocoon on the left hand side and a group of pupae on the right hand side.  The whole cell with the pupae was very sticky.  It looks like these insects have consumed a lot of the pollen/ nectar mixture that the female mason bee had collected for her offspring.
We have never seen this inside a mason bee nesting tunnel, and we are wondering what it is. 

 

Photo #2 is a collection of fruit flies.  Joe has never seen such persistant fruit fly activity as last year (2010).  The question is whether these fruit flies are the same as the pupae in photo number one.  If anyone knows if this is the new Cherry fruit fly, please let us know.

Hartley R. from Vancouver BC, forwarded me a photo taken by Daryl A. from Vancouver, BC and asked for some feedback. 
This blue nesting tray (an Eco-Quicklock corn tray from Beediverse) contains a beneficial wasp pupae.  The adult collects either spiders, aphids or larvae as food for its offspring.  The adult beneficial wasp paralyses the food and then lays an egg on top.  By the end of the summer, the beneficial wasp larvae or grub has eaten its food supply and develops into a pupae.  The pupae overwinters and emerges during the late spring or summer months when temperatures are right.  A great beneficial insect!
It has a very fragile paper like covering so I usually leave it inside the nesting tunnel, reassemble the nesting tray and set it outside again  – ready for next season.